This invention relates to an optical data storage medium, and in particular an optical information recording card. More specifically, the present invention relates to an optical information recording card utilizing specific structural layers.
Much effort has been devoted to the application of optical information techniques to plastic cards. For example, see U.S. Pat. Nos. 4,837,134; 4,835,048; 4,816,362; 4,811,321 and 4,787,075. In conventional information recording cards, which use embossed characters or magnetic stripes for recording, the recording capacity does not always suffice. By applying the technology of optical information recording to plastic cards, optical information recording cards with a read-only memory type having a recording capacity of greater than 200 KB have been reported (see, for example, U.S. Pat. No. 4,835,048). The application of optical information technology to plastic card format therefore holds great promise.
However, problems arise when considering a card format in conjunction with an optical information layer. One major problem is the fact that the card is handled frequently, and with no impunity. Scratching of the optical information layer is therefore a great risk, unless it is protected. Thus, heavy protective overcoat layers are a necessity. Applying such heavy overcoat layers in itself raises problems with respect to maintaining the stability and integrity of the information layer during the manufacturing process. Ease of manufacture is also a major consideration in any commercial process.
Accordingly, it is an object of the present invention to provide one with an optical information card of a structure which is easily and efficiently manufactured.
Another object of the present invention is to provide an optical information card utilizing a naphthalocyanine chromophore containing information layer.
Still another object of the present invention is to provide one with a novel and useful optical information card exhibiting high sensitivity, and which can be easily manufactured while maintaining the integrity of the information layer.
These and other objects and aspects of the present invention will become apparent to the skilled artisan upon a review of the following specification, the Drawing and the claims appended thereto.